Design of 2-D recursive digital filters satisfying prescribed magnitude and constant group delay response

Generation of the 2-variable very-strictly-Hurwitz polynomial (VSHP) using properties of derivatives of even or odd parts of Hurwitz polynomials and their applications in designing 2-D recursive digital filters satisfying prescribed magnitude and constant group delay response is described.     

FORCED CONVECTION HEAT TRANSFER OF INTERACTING SPHERES

A basic understanding of the highly nonlinear interaction effects of closely spaced spheres on fluid mechanics and heat transfer parameters is important for improving the design of a variety of thermal fluid-particle systems. Fluid flow patterns, isotherms, as well as Nusselt number distributions and extended correlations are presented for steady laminar axisym-metric flow past a linear array of three spheres. A finite-element method is used to solve the complete Navier-Stokes and heat transfer equations for the system parameter ranges 1 Re_d  200 (Reynolds number) 2 d_ij10 ( particle spacings)and 0. 1  prRe_d 2000 (Piclet number). The verified computer simulation results indicate that convection heat transfer parameters of interacting spherical particles deviate significantly from solitary spheres for all Reynolds and Piclet numbers.     

Influence of triethanolamine on the hydration characteristics of tricalcium silicate

The hydration characteristics of 3CaO.SiO₂ or β2CaO.SiO₂ are studied by an addition of 0.0, 0.1, 0.5 or 1.0% triethanolamine. The amount of Ca(OH)₂ found at 1, 3, 7 or 28 days was in the order C₃S + 0% TEA > C₃S +0.1% TEA > C₃S + 0.5% TEA > C₃S+1.0% TEA, irrespective of whether lime was estimated by X-ray, DTA, TGA or chemical analysis. The rate of hydration, in terms of the disappearance of 3CaO.SiO₂, showed that hydration proceeded faster in the presence of TEA after 1 day. Additions of TEA increase the induction period, promote the formation of a C-S-H with higher CaO/SiO₂ ratio, increase the formation of non-crystalline Ca(OH)₂ and enhance the surface area of the hydrated silicate product.     

Heat transfer in boundary layer flow of a micropolar fluid past a curved surface with suction and injection

Van Dyke's singular perturbation technique has been used to study the heat transfer in the flow of a micropolar fluid past a curved surface with suction and injection. The conditions for similar solutions of the thermal boundary layer equations have been obtained. In addition to the usual “no slip” condition for velocity, the two types of boundary conditions used for microrotation are: (i) no relative spin on the boundary; (ii) the anti-symmetric part of the stress tensor vanishes at the boundary. The effect of suction or injection on velocity, microrotation, temperature, skin friction coefficient, wall couple stress coefficient, displacement and momentum thicknesses, rate of heat transfer and adiabatic wall temperature have been studied. It is observed that with the increase of injection velocity, the thickness of the boundary layer is increased and the local drag is reduced. A comparison with the results obtained for a Newtonian fluid reveals that the microelements present in the fluid reduce the velocity and frictional drag, and cool the boundary.     

Studies of molybdena-alumina catalysts. X. temperature programmed desorption of H2S and thiophene

Temperature programmed desorption (TPD) and reduction (TPR) studies were carried out on H₂S and thiophene adsorbed on Mo/Al₂O₃ and CoMo/Al₂O₃ catalysts. Freshly sulfided and pyridine poisoned catalysts were run. For sulfided catalysts, the major products of desorption of thiophene were thiophene and butene, leaving a carbonaceous residue. Subsequent TPR in H₂ effected complete removal of the residue with formation of H₂S, thiophene and butene. The residue appeared to consist of an easily reactive thiophene polymer and a less-reactive, sulfur-containing coke. Runs on poisoned catalysts showed less adsorption but product profiles were similar, showing that the adsorption characteristics of the remaining sites were not significantly altered.     

BDN-GWMNN: Internet of Things (IoT) Enabled Secure Smart City Applications

Nowadays, next-generation networks such as the Internet of Things (IoT) and 6G are played a vital role in providing an intelligent environment. The development of technologies helps to create smart city applications like the healthcare system, smart industry, and smart water plan, etc. Any user accesses the developed applications; at the time, security, privacy, and confidentiality arechallenging to manage. So, this paper introduces the blockchain-defined networks with a grey wolf optimized modular neural network approach for managing the smart environment security. During this process, construction, translation, and application layers are created, in which user authenticated based blocks are designed to handle the security and privacy property. Then the optimized neural network is applied to maintain the latency and computational resource utilization in IoT enabled smart applications. Then the efficiency of the system is evaluated using simulation results, in which system ensures low latency, high security (99.12%) compared to the multi-layer perceptron, and deep learning networks.

     

R-Curve Behavior and Flaw Insensitivity of Ce-TZP/Al2O3 Composite

A ceria-partially-stabilized zirconia-aiumina (Ce-TZP/Al₂O₃) composite optimized for transformation toughening was used to demonstrate its flaw insensitivity due to R -curve behavior. Four-point bend specimens fabricated with a controlled distribution of spherical pores showed nearly the same characteristic strength and strength variability (Weibull modulus) as specimens fabricated without the artificial pores. In situ observations confirmed stable growth of cracks initiated at pores and the crack lengths at fracture instability were much greater than the pore sizes, thus resulting in fracture strengths insensitive to the pores. The small variability in the fracture strength was found to be associated with variability in the R -curve and the instability crack lengths. An analysis based on the fracture instability criterion for rising crack growth resistance accounted for the strength variability due to variability in the R -curve. Comparable four-point bend experiments were also conducted on a sintered yttria-partially-stabilized zirconia (2Y-TZP) ceramic. This ceramic showed significant degradation of strength due to the presence of the pores. This flaw sensitivity is attributed to its steep rising R -curve over short crack lengths.     

Pore Structure of Silica Gel

The effect of washing on the texture of silica gel has been investigated in terms of parameters such as porosity, pore size distribution, surface area and absorption of moisture. It was observed that if silica gel (before activation) is washed with water containing dissolved ions such as Ca and Mg wider pores are formed at the expense of smaller ones. This phenomenon has been explained in terms of change in the size distribution of gel particles which is brought about by solution of very fine particles followed by growth, through condensation, of larger particles. The experimental observations have been interpreted to suggest guidelines to control the texture of gels by washing with solutions comaining different cations.     

Record bandwidth, spectrally flat coupling with microbend gratings in dispersion-tailored fibers

We demonstrate resonant grating couplers with the broadest bandwidth (565 nm) reported to date, using microbend gratings in dispersion-optimized few-mode fibers. Control of modal dispersion enables the demonstration of spectrally flat (< 0.25-dB ripple) coupling. This enables a compact (1 cm), broad-band (110 nm) variable optical attenuator, which is highly cost-effective, since device assembly simply involves pressing an as-drawn fiber between two corrugated blocks.